Process for manufacturing 2.3-aminonaphthol compounds



Patented Mar. 22, 1932 UNITED STATES ARTHUR ZITSCHER, OF OFFENIBACH-ON -1HE 'ANILINE WORKS, INC., OF NEW YORK,

-MAIN, GERMANY, ASSIGNOR T GENERAL N. Y., A CORPORATION OF DELAWARE PROCESS FOR MANUFACTURING 2.3-AMINONAPHTHOL COMPOUNDS No Drawing. Application filed December 16,1927, Serial No. 240,630, and in Germany December 24, 1926.

I have found that 2.3-aminonaphthol compounds can be obtained by a smooth reaction, if O-arylsulfonic esters of 3.2-hydroxynaphthalenecarboxyamido compounds '5 of the formula in which formula the naphthalene nucleus may contain further substituents, are subjected to the action of alkali metal salts of the hypochlorous or hypobromous acid according to Hofmannsreaction and if in the 19 formed O-arylsulfonyl-2.8-aminonaphthol compounds of the formula: v

in which formula the naphthalene nucleus may contain further substituents, the arylsulfonic residue is split off by treatment with 5 saponifying agents.

This is a surprising fact, as in the Berichte der Deutschen Chemischen Gesellscha-ft, vol.

58, page 2848, Fries describes his vain efiorts,

to transform the amide'of 2.3-hydroxynapha thoic acid or its ethylcarbonic ester into 3.2- aminonaphthol according to Hofmanns reaction of decomposition.

My new process allows to manufacture 2.3- aminonaphthol and its nuclear substitution products with an excellent yield and in a very pure state. They may be used as intermediates for the production of dyestuffs.

In order to further illustrate my invention the following examples are given, the parts being by weight and all temperatures in centigrade degrees. But I wish to be understood that my invention is not limited to the particular conditions nor to the specific products mentioned therein.

Example 1.341 parts of 3- (para-toluenesulfonyl oxy) -naphthalene-2-carboxyamide (crystallizing from glacial acetic acid as felthke needles, melting at 216 (not corrected), obtainable by acting with para-toluenesulfochloride on 3.2-hydroxynaphthalenecar boxyamide in dilute alkaline solution), are

mixed with spirit and at ordinary temperature a solution of sodium hypochlorite, containing 71 parts of active chlorine, and 250 parts of calcinated soda-are added. The mass is warmed at about for an hour, being slowly dissolved thereby, and then it is heated to boiling for some time. When filtered, the alcohol is mostly distilled off from the mother-liquor and by adding water the2- amino-para-toluene sulfonyl-3-naphthol of the formula:

o-so on;

is separated. When recrystallized from alcohol the new compound is obtained as colorless bright scales melting at Met-145, (not corrected). When treating it with saponifying agents f. i. with an alcoholic caustic soda solution in the heat with a good yield 2.3- aminonaphthol is formed, which may be advantageously isolated as hydrochloric salt. It shows the properties, described in literature.

Example 2-327 parts of 3-(benzenesulfonyl oxy) naphthalene 2 carboxyamide (crystallizing from alcohol or glacial acetic acid as colorless needles, melting at 170, (not corrected) obtainable by acting with benzenesulfochloride on 3.2-hydroxynaphthalenecarbovyaniide in dilute alkaline solution) are suspended in spirit andat ordinary temperature 160 parts of carbonate of soda and a quantity of a sodium hypochlorite solution corresponding to 71 parts of active chlorine, are added. When after some time the mass is dissolved, most of the alcohol is distilled oil and the 2-amino-benzenesulfonyl-3-naphthol, contained in the solution, is saponified by shortly boiling the solution with addition of a caustic soda solution and the 2.3-aminonaphthol, obtained with an excellent yield, is isolated as base or as hydrochloric salt.

Ewample 3.266 parts of 7.-bromo-3-hydroxy-Q-naphthoh'amide (obtained from 7- bromo 3- hydroxy 2 naphthol chloride and ammonia as light yellowish lamellas of the ,ing from F. P. 295 (not corrected)) are dissolved in caustic soda solution and heated to boiling with 210 parts of p-toluene-sulfochloride for a short time. The thus obtained 7-bromo-3- (4-toluenesulfonyl) -oxy naphthalene-2-carboxya-mide of the formula:

a C0-NH:

crystallizes from acetic acid as colorless needles of the'F. P. 184185 (not corrected). By Hofmanns reaction of decomposition this body yields the V 'fonyl) -oxy-2-amino-naphthalene (crystallizdilute alcohol as colorless needles of the F. P. 105 (not corrected) of the formula NH: o-soG-orn which forms by saponification the 7-bromo-2-' amino-3-nap'hthol of the formula:

. B NH| on I It crystallizes from water as colorless thin bright leaflets ofthe F. P. 222 (not corrected). 7

All these products are new compounds. 7 In the same manner other nuclearsubstitution products of 2.3-aminonaphthol may be obtained. I I claim:

1. Process for manufacturing 2.3-aminonaphthol compounds of the formula:

which process comprises subjecting O-arylsulfonlc esters of 3.2-hydroxynaphthalenecarboxyamido compounds of the formula:

0 ONE:

0-S Oa-aryl to the action of alkali metal salts of hypochlorousior hypobromous acid according to Hofmanns reaction of decomposition and spl tting off from the O-arylsulfonyl-2.3- ammonaphthol compounds of the formula:

the arylsulfonic residue by treatment with saponifying agents, in which process in all aforesaid formulas the naphthalene nucleus 7 may contain further substituents.

2. As a new compound 7 -bromo-2-amino-3- naphthol of the formula:

Br NH:

being when dry a colorless powder, crystallizing as thin bright leaflets from water, having a definite melting point, which compound is substantially identical with a product obtainable by subjecting a 7-brom o-3-(arylsul1 fonyl) 'oxy-nap hthalene 2-carboxyamide to the decompositlon reaction of Ho mann and treating the 7-bromo-3-'( arylsulfonyl)' ,oxy 2-amino-naphthalene thus formed with saponifying agents. I

3. In the process for producing 2.3-aminonaphthol compounds the manufacture of 0-.

'arvlsulfonyl-2.3-aminonaphthol compounds of the formula o -soraryl which comprises subjecting O-arylsulfonic esters of 3.2-hydroxy-na hthalene-carboxye amido compounds of the ormula:

in which formula the naphthalene nucleus may contain further substituents, being crystalline colorless substances, having a definite i melting point which compounds are substantially identical with productsobtainable by subjectin O-arylsulfonic' esters of 3.2 hydroxyna ihthalene-carboxyamido compounds to the action of alkali metal salts of hypochlorous or hypobromous acid according to Hofmanns reaction of decomposition. In testimony whereof, I aflix'my signature.

Y ARTHUR ZITSCHER. 

